Science Facing Aliens - Invasive Alien Species in Belgium - Belgian ...

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F. japonica has lower SLA (Figure 3) but higher N resorption efficiency (up to 70% N is
resorbed from senescing leaves, vs. 40% in F. sachalinensis) than the two other taxa (Figure
4). F. sachalinensis has higher N content than the two other taxa. F. ×bohemica is
intermediate between its parents for most traits.
This monitoring of functional traits will be carried on from April to July 2009. SLA,
leaf water, nitrogen and carbon content will also be measured again. Field observations will
be complemented by a “semi-controlled conditions” experiment to test if the three taxa show
contrasting phenotypic plasticity of functional traits in response to different soil fertility
conditions. For this, rhizomes were taken from seven knotweed populations (two F. japonica,
two F. sachalinensis and three F. ×bohemica). They were planted in twenty litre pots, with
different doses of NPK fertilizer. Their functional traits will be monitored from 2009 to the
end of 2010.
Height (cm)
350,00
300,00
250,00
200,00
150,00
100,00
50,00
0,00
Growth
0 14 28 42 56 70 84 98 112 126 140
Time (days since the 17th of March)
F jap
F boh
F sach
Figure 1: Monitoring of the main axis height of the three Fallopia taxa. Bars indicate the standard
error.
Number of leaves on the
main axis
Variation of the number of leaves on the main axis
30,00
25,00
20,00
15,00
10,00
5,00
0,00
0 50 100 150
Time (days since the 17th of March)
F jap
F boh
F sach
Figure 2: Monitoring of the number of leaves on the main axis of the three Fallopia taxa. Bars
indicate the standard error.